lib/uglifier.rb in uglifier-4.1.20 vs lib/uglifier.rb in uglifier-4.2.0

@@ -96,10 +96,11 @@
     :define => {}, # Define values for symbol replacement
     :keep_fnames => false, # Generate code safe for the poor souls relying on Function.prototype.name at run-time. Sets both compress and mangle keep_fanems to true.
     :toplevel => false,
     :ie8 => true, # Generate safe code for IE8
     :source_map => false, # Generate source map
+    :error_context_lines => 8, # How many lines surrounding the error line
     :harmony => false # Enable ES6/Harmony mode (experimental). Disabling mangling and compressing is recommended with Harmony mode.
   }
 
   EXTRA_OPTIONS = [:comments, :mangle_properties]
 
@@ -147,13 +148,10 @@
   def initialize(options = {})
     (options.keys - DEFAULTS.keys - EXTRA_OPTIONS)[0..1].each do |missing|
       raise ArgumentError, "Invalid option: #{missing}"
     end
     @options = options
-
-    source = harmony? ? source_with(HarmonySourcePath) : source_with(SourcePath)
-    @context = ExecJS.compile(source)
   end
 
   # Minifies JavaScript code
   #
   # @param source [IO, String] valid JS source code.
@@ -178,10 +176,17 @@
     run_uglifyjs(source, true)
   end
 
   private
 
+  def context
+    @context ||= begin
+      source = harmony? ? source_with(HarmonySourcePath) : source_with(SourcePath)
+      ExecJS.compile(source)
+    end
+  end
+
   def source_map_comments
     return '' unless @options[:source_map].respond_to?(:[])
 
     suffix = ''
     if @options[:source_map][:map_url]
@@ -211,28 +216,80 @@
       :parse => parse_options,
       :sourceMap => source_map_options(input_map),
       :ie8 => ie8?
     }
 
-    parse_result(@context.call("uglifier", options), generate_map)
+    parse_result(context.call("uglifier", options), generate_map, options)
   end
 
   def harmony?
     @options[:harmony]
   end
 
-  def error_message(result)
-    result['error']['message'] +
-      if result['error']['message'].start_with?("Unexpected token") && !harmony?
-        ". To use ES6 syntax, harmony mode must be enabled with " \
-        "Uglifier.new(:harmony => true)."
+  def harmony_error_message(message)
+    if message.start_with?("Unexpected token")
+      ". To use ES6 syntax, harmony mode must be enabled with " \
+      "Uglifier.new(:harmony => true)."
+    else
+      ""
+    end
+  end
+
+  def error_context_lines
+    @options.fetch(:error_context_lines, DEFAULTS[:error_context_lines]).to_i
+  end
+
+  def error_context_format_options(low, high, line_index, column)
+    line_width = high.to_s.size
+    {
+      :line_index => line_index,
+      :base_index => low,
+      :line_width => line_width,
+      :line_format => "\e[36m%#{line_width + 1}d\e[0m ", # cyan
+      :col => column
+    }
+  end
+
+  def format_error_line(line, options)
+    # light red
+    indicator = ' => '.rjust(options[:line_width] + 2)
+    colored_line = "#{line[0...options[:col]]}\e[91m#{line[options[:col]..-1]}"
+    "\e[91m#{indicator}\e[0m#{colored_line}\e[0m"
+  end
+
+  def format_lines(lines, options)
+    lines.map.with_index do |line, index|
+      if options[:base_index] + index == options[:line_index]
+        format_error_line(line, options)
       else
-        ""
+        "#{options[:line_format] % (options[:base_index] + index + 1)}#{line}"
       end
+    end
   end
 
-  def parse_result(result, generate_map)
-    raise Error, error_message(result) if result.has_key?('error')
+  def context_lines_message(source, line_number, column)
+    return if line_number.nil?
+
+    line_index = line_number - 1
+    lines = source.split("\n")
+
+    first_line = [line_index - error_context_lines, 0].max
+    last_line = [line_number + error_context_lines, lines.size].min
+    options = error_context_format_options(first_line, last_line, line_index, column)
+    context_lines = lines[first_line...last_line]
+
+    "--\n#{format_lines(context_lines, options).join("\n")}\n=="
+  end
+
+  def error_message(result, options)
+    err = result['error']
+    harmony_msg = harmony? ? '' : harmony_error_message(err['message'].to_s)
+    src_ctx = context_lines_message(options[:source], err['line'], err['col'])
+    "#{err['message']}#{harmony_msg}\n#{src_ctx}"
+  end
+
+  def parse_result(result, generate_map, options)
+    raise Error, error_message(result, options) if result.has_key?('error')
 
     if generate_map
       [result['code'] + source_map_comments, result['map']]
     else
       result['code'] + source_map_comments